1. Field of the Invention
The present invention relates generally to underwater vehicle buoyancy systems and in particular, to methods for the manufacture of flotation spheres used in these systems.
2. Statement of Prior Art
Hollow spheres have been used as an integral part of underwater vehicle buoyancy systems for a number of years. In order to design a sphere which meets design criteria including strength of the sphere, buoyancy, and weight in air, several sets of equations must be solved in an iterative process for each of the candidate spheres under consideration. The end solutions from each equation must then be compared and an appropriate sphere design selected.
Once the sphere design is selected, manufacture is accomplished by one of several methods. In one method, a skilled machinist enters the geometric data of the selected sphere into the Controller computer program of a numerically controlled (NC) machine. One such machine is the LeBlond Computer Numerical Control Lathe machine with a General Electric Mark Century 1050 controller. The NC machine, under the supervision of a skilled machinist, forms two finished hemispheres of the specified geometry from hollow rough-formed hemispherical forgings or castings. The two finished hemispheres are then joined by welding or gluing to form a finished flotation sphere.
In another method the skilled machinist uses geometric data directly. The machinist uses the geometric data with a lathe and template to form two finished hemispheres of the specified geometry from hollow rough formed hemispherical forgings or castings. The two finished hemispheres are joined by welding or gluing to form a finished flotation sphere.
Even with the use of calculators, the required computations for sphere design are very time intensive and the accuracy of the results is often adversely affected by human error during data entry and equation solving.
As a result, the prior art methods have continuing deficiencies in system solution time for sphere design, accuracy of design solutions, and complexity of choosing one sphere design from several candidate spheres.